Partitioning of adipose lipid metabolism by altered expression and function of PPAR isoforms after bariatric surgery

• Published in: International Journal of Obesity Vol. 42; no. 2; pp. 139 - 146
• Main Authors: Jahansouz, C, Xu, H, Hertzel, A V, Kizy, S, Steen, K A, Foncea, R, Serrot, F J, Kvalheim, N, Luthra, G, Ewing, K, Leslie, D B, Ikramuddin, S, Bernlohr, D A
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-02-2018; Nature Publishing Group
• Subjects: 631/443/319; 631/80/86; 692/163/2743/393; 692/308/575; 692/700/565/545/2098; Adipose tissue; Adult; Bariatric Surgery; Care and treatment; Carnitine; Cell receptors; Complications and side effects; Cysteine; Desaturase; Diabetes mellitus; Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Type 2 - prevention & control; Dietary restrictions; Epidemiology; Fatty acid-binding protein; Fatty Acid-Binding Proteins - metabolism; Fatty acids; Female; Gastrectomy; Gastric bypass; Gastrointestinal surgery; Gene expression; Gene Expression Regulation; Glucose metabolism; Health aspects; Health Promotion and Disease Prevention; Humans; Immunoblotting; Internal Medicine; Isoforms; Lipid metabolism; Lipid Metabolism - physiology; Lipid peroxidation; Lipids; Lipolysis; Lipolysis - physiology; Male; Medicine; Medicine & Public Health; Metabolic Diseases; Metabolism; Mitochondria; Mitochondrial uncoupling protein 2; Nuclear receptors; Obesity; Obesity, Morbid - metabolism; Obesity, Morbid - surgery; original-article; Oxidation; Oxidative stress; Patients; Peroxisome proliferator-activated receptors; Peroxisomes; Physiological aspects; PPAR delta - physiology; Proteins; Public Health; Receptors; Stearoyl-CoA desaturase; Subcutaneous Fat - metabolism; Surgery; Thermogenesis; Treatment Outcome; Uncoupling Protein 2 - metabolism
• ISSN: 0307-0565; 1476-5497
• DOI: 10.1038/ijo.2017.197

Background:
Bariatric surgery remains the most effective treatment for reducing adiposity and eliminating type 2 diabetes; however, the mechanism(s) responsible have remained elusive. Peroxisome proliferator-activated receptors (PPAR) encompass a family of nuclear hormone receptors that upon activation exert control of lipid metabolism, glucose regulation and inflammation. Their role in adipose tissue following bariatric surgery remains undefined.
Materials and Methods:
Subcutaneous adipose tissue biopsies and serum were obtained and evaluated from time of surgery and on postoperative day 7 in patients randomized to Roux-en-Y gastric bypass (
n
=13) or matched caloric restriction (
n
=14), as well as patients undergoing vertical sleeve gastrectomy (
n
=33). Fat samples were evaluated for changes in gene expression, protein levels, β-oxidation, lipolysis and cysteine oxidation.
Results:
Within 7 days, bariatric surgery acutely drives a change in the activity and expression of PPARγ and PPARδ in subcutaneous adipose tissue thereby attenuating lipid storage, increasing lipolysis and potentiating lipid oxidation. This unique metabolic alteration leads to changes in downstream PPARγ/δ targets including decreased expression of fatty acid binding protein (FABP) 4 and stearoyl-CoA desaturase-1 (SCD1) with increased expression of carnitine palmitoyl transferase 1 (CPT1) and uncoupling protein 2 (UCP2). Increased expression of UCP2 not only facilitated fatty acid oxidation (increased 15-fold following surgery) but also regulated the subcutaneous adipose tissue redoxome by attenuating protein cysteine oxidation and reducing oxidative stress. The expression of UCP1, a mitochondrial protein responsible for the regulation of fatty acid oxidation and thermogenesis in beige and brown fat, was unaltered following surgery.
Conclusions:
These results suggest that bariatric surgery initiates a novel metabolic shift in subcutaneous adipose tissue to oxidize fatty acids independently from the beiging process through regulation of PPAR isoforms. Further studies are required to understand the contribution of this shift in expression of PPAR isoforms to weight loss following bariatric surgery.